LCD devices are commonly used as displays for compact electronic apparatuses, because they provide good quality images with little power consumption and are very thin. The liquid crystal material in an LCD device does not emit light. The liquid crystal material must be lit by a light source to clearly and sharply display text and images. Thus, a backlight module is generally needed for an LCD device.
Referring to FIG. 13, a typical LCD device 1 includes a display panel 19 and a backlight module 10 opposite to the display panel 19. The backlight module 10 is a direct type backlight module, and includes a metal back frame 15, a plurality of light sources 14, a diffuser 11, and a brightness enhancement film (BEF) 12. The plurality of light sources 14, the diffuser 11, and the BEF 12 are accommodated in the metal back frame 15 in that order from bottom to top.
Each light source 14 is a light bar, which includes a base 141 and a plurality of light emitting elements 142 disposed on the base 141. Some circuits (not shown) disposed on the base 141 are used for electrically connecting an external power supply (not shown) to the light emitting elements 142. The external power supply provides power to the light emitting elements 142, enabling the light emitting elements 142 to emit light beams. The light beams emitted from the light emitting elements 142 are provided to the display panel 19 via the diffuser 11 and the BEF 12.
The metal back frame 15 includes a bottom plate 151 and side walls 150 extending perpendicularly from the edges of the bottom plate 151. The bottom plate 151 and the side walls 150 define an accommodating space (not labeled). The plurality of light sources 14, the diffuser 11, and the BEF 12 are received in the accommodating space.
When the backlight module 10 is assembled, the light sources 14 are placed on the bottom plate 151 of the back frame 15 and arranged in an array. Two ends (not labeled) of each light source 14 are affixed to the bottom plate 151 using screws (not labeled). An additional screw (not labeled) can be used to fasten the middle part (not labeled) of the light source 14 to the bottom plate 151.
Thus, the backlight module 10 needs plural screws to affix the light sources 14 to the bottom plate 151 of the back frame 15. The larger the size of the backlight module 10, the more screws that will be needed. Screws make assembling and disassembling the light sources 14 unduly inconvenient and inefficient. Furthermore, the base 141 of the light source 14 needs to be thin for better thermal conductivity. But the base 141 is liable to warp and lose contact with the bottom plate 151 if it is too thin. Thus conduction of heat away from the light source 14 decreases when the base 141 becomes thinner.
Therefore, an improved backlight module is desired to overcome the above-described deficiencies.